Line a strainer with 4 layers of cheesecloth or 1 coffee filter and place over a bowl. Place yogurt in prepared strainer and cover with edges of cheesecloth. Refrigerate for 8 hours or overnight. In a small bowl, combine the strained yogurt, cucumber, vinegar and mint., Spread hummus in the bottom of a 9-in. deep dish pie plate. Layer with onion, peppers, feta cheese, olives, tomatoes and yogurt mixture. Top with parsley and additional mint if desired. Chill until serving., Cut each pita half into 3 wedges; separate each wedge into 2 pieces. Place in a single layer on ungreased baking sheets. Brush both sides with olive oil; sprinkle with salt and pepper., Bake at 400° for 8-10 minutes or until crisp, turning once. Serve with dip.